This invention relates generally to apparatus and methods for generating coherent electromagnetic radiation, and, more particularly, relates to free electron lasers (FEL) for generating coherent radiation over a range of wavelengths, including far infra-red (FIR) submillimeter regions.
The importance of a versatile and convenient FIR submillimeter source is a direct consequence of the large range of research opportunities and technical applications associated with this spectral region. Examples of such opportunities are found in spectroscopy and in other areas of technology development.
Spectroscopy applications include surface science, condensed-matter phenomena, excitations in high critical temperature superconductors, laser chemistry, radio astronomy, diagnostics in thermonuclear plasmas, conformational excitations in biomolecules, and gas phase spectroscopy. Technology development activities include submillimeter radar, radar modeling, countermeasures for FIR systems, space communications, compact high-gradient accelerator research, plasma heating, and isotope separation.
In view of the importance of this spectral range, considerable effort has been expended in developing new sources. Increased source power automatically provides greater signal-to-noise ratio, and, if stability is adequate, better resolution. Furthermore, the study and exploitation of nonlinear and transient processes that are not possible with low-power sources now become accessible options. Thus, recent years have seen new additions to the class of FIR submillimeter sources, including microwave tubes, impatt diodes, gyrotrons, FIR lasers, FELS, and Smith-Purcell devices.